Small test for dementia of Alzheimer’s type

Authors


Professor Haruo Kashima, MD, PhD, Department of Neuropsychiatry, Keio University, School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-0016, Japan. Email: kashima@sc.itc.keio.ac.jp

At present, diverse tests are available for the diagnosis and assessment of dementia, including comprehensive tests (Wechsler Adult Intelligence Scale Revised (WAIS-R), etc.) and smaller tests such as the Hasegawa Dementia Scale-Revised (HSD-R) and Mini-Mental State Examination (MMSE). In the present paper, results of the small test for dementia of Alzheimer’s type that the author has been using for the assessment of Alzheimer’s dementia at our outpatient clinic at the Keio University Hospital (Tokyo) are presented.

It is known that patients with dementia of Alzheimer’s type show diffuse brain atrophy. However, it is incorrect to say that the whole brain becomes atrophic in these patients. For example, no evidence of atrophy is observed in the areas involved in sensation or motor function (the so-called “projection areas”). However, marked atrophy is indeed seen in and around the hippocampus (located in the medial brain), in the (temporo)-parietal areas and in the frontal areas (anterolateral areas of the brain) in these patients. The author has devised a small and convenient test comprised of tasks related to the specific functions associated with these three aforementioned areas showing marked brain atrophy (functions of memory, visuo-spatial manipulation and exchange of acts or ideas) and tasks related to disorders of attention (general attention) arising nonspecifically from brain damage. This test has been used at our clinic for the diagnosis and evaluation of dementia of Alzheimer’s type and are presented below.

1. TASKS FOR ATTENTIONAL FUNCTION

Attentional function serves as the basis for other cognitive functions. If attentional function is disturbed, most cognitive functions are also disturbed. For this reason, evaluation of attentional function is indispensable for the evaluation of brain function. Two tasks are used for the evaluation of attentional function. In the first (“digit span forward task”), the examiner reads out a sequence of numbers, for example “5 2 9 4 3 1”, and asks the examinee to immediately repeat the numbers in the same sequence. In the other (“digit span backward task”), the examinee is asked to repeat the numbers immediately in the reverse sequence (e.g. “3 1 8” if the examiner has said “8 1 3”). Attentional function is rated as satisfactory if the examinee can correctly perform the span forward task for seven numbers and the digit span backward task for five numbers. If the performance in the digit span backward task is much poorer than that in the digit span forward task, dysfunction of the temporo-parietal area may be suspected, as described later in this paper.

2. TASK FOR MEMORY FUNCTION: AUDITORY-VERBAL LEARNING TEST (SEVEN WORDS)

This task involves memorization of seven words: “ship (Japanese: fu-ne)”, “mountain (ya-ma)”, “dog (i-nu)”, “fiver (ka-wa)”, “wood (mo-ri)”, “night (yo-ru)” and “bicycle (ji-te-n-shi-ya)”. The examiner tells the examinee: “Now, I shall say seven words. Please listen to them carefully and memorize them. Then, please remember and repeat the words in the same sequence to the extent that you can remember”. Memorizing all of the seven words at once is often difficult even for normal controls, and they need to hear the words twice or thrice to memorize all of them. This task is aimed at evaluating the characteristics of individuals in terms of the volume and way of memorization. Performance in this task allows estimation to some extent as to whether the memory disturbance in an examinee is of ordinary type or attributable to some other factors.

Of the seven words used for this task, the first word “fu-ne” and the last word “ji-te-n-shi- ya” are the easiest to memorize. Furthermore, the word “ji-te-n-shj-ya” is composed of five syllables, unlike the other words that are composed of only two syllables, and therefore draws more attention than the other words. If an examinee cannot remember these two words (that is, the first and the last), then it is likely that the examinee has a problem at the vigilance level or is influenced by distraction, rather than having a memory disorder. The sequence in which the words are remembered after being heard twice or thrice suggests to some extent the examinee’s strategy of memorization. After listening twice, some examinees first remember the words they remembered after the first round of hearing and other examines first remember the words they failed to remember after the first round of hearing. This sequence reflects the examinee’s strategy for memorization. In other words, it allows estimation of the degree and quality of the memory disorder. For most patients with dementia of Alzheimer’s type, full memorization of the seven words is difficult even after five rounds of hearing, and they often can remember only four or five words after five repetitions of the words. In patients with memory disorder, the performance in this word memorization task is poorer if they undergo the task after some other tasks.

3. TASK FOR VISUO-SPATIAL FUNCTION

Damage of the (temporo-)parietal areas can cause symptoms such as “inability lo know where the patient is now located” or “going astray”. “Loss of the ability to return washed dishes to the right place” is also attributable to damage of the (temporo-)parietal areas. The last case is often associated with memory disorder, that is, loss of memory about where the dishes should be returned to, and it can be explained by disorientation of the individual within the kitchen. Individuals showing this kind of disorder cannot correctly move their body in three dimensions. For example, they are sometimes unable to fold washed clothes appropriately. Patients with dementia of Alzheimer’s type often present with disturbance of visuo-spatial manipulations (symptoms associated with damage to the (temporo-)parietal areas) soon after the onset of the disease. As a means of evaluating visuo-spatial manipulations, the author has been using the task of forming various shapes with fingers. This task is simple but highly sensitive. For example, the shape of a fox (as seen in shadow pictures) is formed with both hands, and one hand is twisted half way to unite the two foxes (called “reverse-fox”). The examiner forms the reverse-fox with his/her hands and then tells the examinee: “Please do this by yourself”. Individuals who can smoothly form the reverse-fox are highly unlikely to have dementia of Alzheimer’s type if they manifest signs of memory disorder. In contrast, because elderly people are often unable to fulfill this task, it is difficult to arrive at any definitive conclusion in elderly examinees who cannot accomplish this task.

Visuo-spatial manipulation can also be tested using the task of copying figures. Of the above-mentioned tasks for attentive function, the digit span backward task often involves writing figures on the examinee’s head and asking the examinee to read the written figures in a reverse sequence. Performance in this task is sometimes closely related to visuo-spatial function. If performance in the digit span forward task is satisfactory, but that in the digit span backward task is markedly poor, the examinee may have disturbed visuo-spatial manipulation (i.e. dysfunction of the (temporo-)spatial areas); dementia of Alzheimer’s type may, therefore, be suspected in such a case.

4. TASK FOR EXCHANGE OF ACTS

Damage of the frontal areas can disturb exchange of acts or ideas. For example, patients with this type of damage present with symptoms such as “inability to skillfully switch from a current idea to another” or “tendency to continue the same thought once it has been initiated”. These symptoms are collectively called “perseveration” or “loss of flexibility in thoughts”. The “fist-palm test (Guu-paa test)” is used as a task to assess the ability to exchange acts or cognitions. In this task, the examinee is first asked to form a “fist (guu)” with the left hand and “palm (paa)” with the right hand, then to form “palm” with the left hand and “fist” with the right hand, and subsequently to use the hands alternately for formation of “palm” and “fist”. Patients with frontal lobe damage are often unable to exchange the hands and tend to form only “fist” or “palm” with both hands. The author also uses a task designed to evaluate exchange of acts or cognitions at a higher level (idea manipulation). In this task, pieces of paper of three different sizes (large, medium and small), three colors (red, blue and green) and three shapes (circle, triangle and square) are used. The examiner tells the examinee: “Please classify these pieces of paper”. Most examinees divide the pieces by color into three groups. The examiner then says: “Please classify them in a different way”. That is, the examinee is required to switch from the color-based classification to shape- or size-based classification. In other words, the examinee must switch from the idea of color-based classification to another way of classification. This task is designed to evaluate the ability to smoothly exchange between ideas.

A small and convenient test devised by the author for the diagnosis and evaluation of dementia of Alzheimer’s type are presented. In cases of aging-related forgetfulness, no marked abnormality is usually found in any of the tests designed to evaluate the functions of the temporo-parietal areas, even though the performance in the memory task may be poor. In cases of dementia of Alzheimer’s type (even in cases with mild dementia of this type), not only memory disorder but also poor performance in tests designed to assess the integrity of the temporo-parietal areas and frontal areas is often noted. Memory disorder is a key symptom of dementia of Alzheimer’s type, but it is not the only symptom of this type of dementia and overall assessment of the memory disorder and other symptoms is crucial in distinguishing dementia of Alzheimer’s type from aging-related forgetfulness.

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